Interventional catheter for retrograde use having embolic protection capability and methods of use

ABSTRACT

Interventional catheters are disclosed for use in performing diagnostic and therapeutic procedures in vessels that are accessed retrograde to blood flow. The catheters include an elongated shaft slidably disposed within a sheath, a distal region having an end effector and a filter disposed proximal to the end effector to capture emboli liberated during the diagnostic or therapeutic procedure. The filter includes a plurality of struts that cooperate with an exterior surface of the catheter to define a reservoir to retain captured emboli, the reservoir configured so that advancement of the sheath contracts the filter without squeezing or dislodging captured emboli beyond a distal end of the filter.

FIELD OF THE INVENTION

The present invention relates generally to catheters for performinginterventional procedures, such as angioplasty and/or stenting, invessels where there is a risk of the release of one or more emboli. Inparticular, the present invention is designed for use in instances wherethe target vessel is accessed distal to the lesion or in the so-called“retrograde” fashion as in the iliac arteries when approached viaipsilateral femoral access.

BACKGROUND OF THE INVENTION

Interventional techniques have been developed wherein catheters are usedto perform diagnostic and therapeutic procedures, such as stenting andangioplasty. During such procedures, thrombus, plaque, or other materialmay be released into the bloodstream as emboli. If free to circulatethrough the body, emboli may become lodged in the smaller distal vesselsoften with serious consequences, thereby presenting a risk oflife-threatening or limb threatening ischemia.

U.S. Pat. No. 5,011,488 to Ginsburg, for example, describes a catheterdesigned to remove frangible thrombus from a vessel, such as from a A-Vfistula, to restore flow through the vessel and reduce the risk thatthrombus may dislodge and migrate to other regions of the patient'svasculature. The catheter comprises three concentrically arrangedflexible tubes, wherein the innermost tube has at its distal end anexpandable body and the central tube has an expandable funnel-shapedmember. In operation, the funnel-shaped member is deployed proximal ofthe thrombus while the innermost tube and expandable member are advancedto a position distal of the thrombus. The expandable member then isdeployed to contact the vessel wall and retracted proximally to urge thethrombus into the funnel-shaped member. U.S. Pat. No. 5,102,415 toGuenther et al. describes another multi-catheter device for use inremoving blood clots.

The devices described in the foregoing patents have severaldisadvantages that limit their utility. First, the presence of multipleconcentric catheters increases the delivery profile and rigidity of thedevice. Second, the devices are configured primarily to remove frangiblethrombus, and are expected to be unsuitable for removing calcified ordense lesions without inflicting trauma to the vessel endothelium.Third, the configuration of the funnel-shaped components and retractableinnermost catheter are incompatible with dilatation or stent deliveryfunctionality.

U.S. Pat. No. 5,549,626 to Miller et al. describes a vena cava filterincluding a self-expanding mesh basket affixed to the distal end of aninner catheter enclosed within a delivery sheath. Suction may be appliedthrough the inner catheter to remove emboli captured in the basket. Asin the Ginsburg and Guenther patents, the device described in Miller isnot appropriate for use in connection with stent delivery or vesseldilatation.

U.S. Pat. No. 4,723,549 to Wholey describes a catheter having anexpandable filter mounted to the catheter shaft distal to a dilatationballoon. The filter comprises a plurality of ribs that are preformed tostow against the catheter. A balloon located between the ribs andcatheter causes the ribs to deploy radially outward when inflated. Theribs and filter return to the collapsed position when the balloon isdeflated.

The device described in the foregoing Wholey patent contemplatesantegrade blood flow, i.e., in a proximal to distal direction along thecatheter shaft. Accordingly, the device described in the Wholey patentwould not be suitable for capturing emboli in the retrograde accessapplications, such as in the iliac arteries. In addition, there is arisk that, when the balloon deflates and the ribs collapse against thecatheter shaft, some of the emboli collected in the filter may besqueezed past the end of the filter and escape into the bloodstream.

U.S. Pat. No. 6,042,598 to Tsugita et al. describes a variety ofpercutaneous catheter-based embolic filters. That patent discloses anumber of filters that may be deployed from a distal end of a catheter.Like the filter in the aforementioned Wholey patent, however, suchfilters are not suitable for retrograde access applications, because theemboli are generally released downstream of the filters. In addition,FIG. 10 of Tsugita et al. depicts a catheter for use in retrogradeaccess applications in which the filter assembly is coupled directly tothe outer surface of the catheter. Such an arrangement is undesirablebecause it permits movements of the catheter to be directly transferredto the filter, thus creating the risk that emboli may escape past theouter edge of the filter. More importantly, however, the filterdescribed with respect to FIG. 10 does not provide any mechanism forpreventing large amounts of embolic material from being squeezed out ofthe filter by the sheath during filter contraction and removal of thecatheter.

U.S. Patent Application Publication No. US2002/0095172 to Mazzocchi etal. describes various embolic filters that attempt to prevent embolifrom escaping filters when they are contracted for removal. The filterof FIGS. 13-15 comprises a basket having a cover slidably disposed toengage the basket and thereby retain emboli within the filter. However,the relative complexity of the filters described in that applicationwould appear to limit the utility of those designs.

In view of the foregoing, it would be desirable to provide a catheterfor use in an interventional procedure in retrograde accessapplications, such as the iliac vessels, wherein the catheter has anembolic protection capability and provides a reduced insertion profile.

In view of the foregoing, it would be desirable to provide a catheterfor use in an interventional procedure in retrograde accessapplications, such as the iliac vessels, wherein the catheter has anembolic protection capability and a simple design that avoids the use ofmultiple concentric catheters.

It further would be desirable to provide a catheter for use in aninterventional procedure in retrograde access applications, wherein thecatheter has an embolic protection capability and does not requiresuction or aspiration, thereby obviating the need to provide a suctionor aspiration lumen and enabling a smaller insertion profile.

It also would be desirable to provide a catheter for use in aninterventional procedure in retrograde access applications, wherein thecatheter has an embolic protection capability and reduces the risk thatemboli will be dislodged from the device during filter contraction andremoval of the catheter.

SUMMARY OF THE INVENTION

In view of the foregoing, it is an object of the present invention toprovide a catheter for use in an interventional procedure that requiresretrograde access, such as the iliac vessels, wherein the catheter hasan embolic protection capability and provides a reduced insertionprofile.

It is another object of the present invention to provide a catheter foruse in an interventional procedure in retrograde access applications,such as the iliac vessels, wherein the catheter has an embolicprotection capability and a simple design that avoids the use ofmultiple concentric catheters.

It is also an object of this invention to provide a catheter for use inan interventional procedure in retrograde access applications, whereinthe catheter has an embolic protection capability and does not requiresuction or aspiration, thereby obviating the need to provide a suctionor aspiration lumen and enabling a smaller insertion profile.

It is a further object of the present invention to provide a catheterfor use in an interventional procedure in retrograde accessapplications, wherein the catheter has an embolic protection capabilityand reduces the risk that emboli will be dislodged from the deviceduring contraction and removal of the catheter.

These and other objects of the present invention are accomplished byproviding an interventional catheter for use in retrograde accessapplications, such as the iliac arteries, having a filter that capturesand securely retains emboli within a reservoir when the filter iscollapsed for removal from the vessel. In a preferred embodiment, thecatheter comprises a catheter having a therapeutic or diagnostic endeffector, e.g., a balloon for dilatation or stent delivery, a filterdisposed on the catheter shaft proximal of the end effector and areservoir disposed between the filter and the end effector. The devicepreferably further comprises a delivery sheath that surrounds thecatheter and assists in retracting the filter to its deliveryconfiguration.

When used to treat stenotic lesions occurring in an artery that requiresretrograde access, such as an iliac artery being treated from theipsilateral femoral artery, the catheter is advanced through the arteryuntil the end effector is disposed within the lesion, as may bedetermined by radiography. The sheath then is withdrawn proximallybeyond the end effector and filter, allowing the filter to deploy. Theend effector then is actuated to perform a desired diagnostic ortherapeutic function, e.g., a balloon is inflated to dilate the lesionand/or deploy a stent and restore patency to the vessel.

In accordance with the principles of the present invention, embolireleased during actuation of the end effector are captured in the filterand directed into the reservoir. Upon completion of the interventionalprocedure, the sheath and inner catheter are moved relative to oneanother to collapse the filter, thereby sealing the emboli within thereservoir and reducing the risk of an inadvertent release of particles.The catheter then is removed from the patient.

In one embodiment, the reservoir constitutes a reduced diameter sectionof the catheter shaft. In this embodiment, when the filter is contractedagainst the catheter shaft by advancement of the sheath, the filterspans the reduced diameter section of the shaft and imparts no squeezingmotion to the captured embolic material. Accordingly, the capturedembolic material cannot be squeezed past the distal end of the filterand is securely retained in the reservoir.

In an alternative embodiment, filter mesh has an amphora shape whereinthe distal ends of the struts that support the filter mesh include aconcave indentation, so that the proximal portion of the filter definesa reservoir. The indentation is configured so that when the sheath isadvanced to contract the struts, the distal ends of the filter contactthe catheter shaft before more proximal portions of the struts, andprevent embolic material from being dislodged from the filter in adistal direction.

Methods of using devices constructed in accordance with the presentinvention also are provided.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and advantages of the present invention willbe apparent upon consideration of the following detailed description,taken in conjunction with the accompanying drawings, in which likereferenced characters refer to like parts throughout, and in which:

FIGS. 1A and 1B are side views of a prior art catheter for use inretrograde access applications depicting some of the shortcomings ofsuch designs;

FIG. 2 is a side view of an exemplary embodiment of an interventionalcatheter of the present invention;

FIGS. 3A and 3B are side sectional views of the device depicted in FIG.1 taken along the line A-A when in a contracted and a deployed state,respectively;

FIGS. 4A and 4B are side views of an embodiment of a self-expandingmember in closed and open states, respectively;

FIGS. 5A to 5F are side views illustrating steps of using the device ofFIG. 1; and

FIGS. 6A and 6B are side sectional views of an alternative embodiment ofa filter suitable for use in the catheter of the present invention,deployed within a vessel and in a contracted state, respectively.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to an interventional catheter for usein the retrograde access applications, such as the iliac arteries, thatincludes an embolic protection system. In an iliac stenting procedure,for example, an interventional catheter is inserted percutaneously orthrough a cut-down in the patient's groin in the region of the femoralartery, whereby the blood flows towards the device along the cathetershaft, i.e., from the distal end of the device towards its proximal end.A catheter that incorporates a filter element located distal to thedilatation or stent delivery balloon, such as the above-described U.S.Pat. No. 4,723,549 to Wholey, cannot practically be used in such aprocedure, since any emboli liberated will be carried away from thefilter.

Referring to FIG. 1A, the stent delivery system and filter arrangementdepicted in FIG. 10 of the foregoing U.S. Pat. No. 6,042,598 to Tsugitaet al. is reproduced. Stent delivery system 10 comprises catheter 11having stent 12 disposed on balloon 13, filter 14 and sheath 15 slidablydisposed on catheter 11. Filter 14 comprises filter mesh 16 affixed toself-expanding struts 17. Sheath 15 retains struts 17 contracted againstthe shaft of catheter 11 during insertion of the catheter. Sheath 15then is retracted proximally so that struts 15 self-expand and deployfilter mesh 16 to the funnel shape depicted in FIG. 1A. To ensure thatemboli do not escape past the outer edge of filter 14, open end 18 ofthe filter contacts the vessel wall.

Stent delivery system 10 provides a filter suitable for use inretrograde access applications, i.e., where blood flows from the distalto the proximal catheter direction, as indicated by arrow A. Emboli Eliberated during the stent delivery and dilatation procedure arecaptured in filter mesh 16. Upon completion of the interventionalprocedure, sheath 15 is advanced distally to collapse the filter andpermit retrieval of the catheter. Alternatively the filter may have anatraumatic outer surface such that the catheter may be retracted intothe sheath to close the filter.

Referring to FIG. 1B, a principal drawback of the foregoing prior artcatheter system is described. In particular, when sheath 15 is advancedforward, it causes struts 17 and filter mesh 16 to collapse against theshaft of catheter 11 in a proximal to distal direction. This is expectedto squeeze captured embolic material distally towards open end 18 offilter 14, where it can escape from the filter into the bloodstream. Thepresent invention is directed to solving this problem.

In accordance with the principles of the present invention, theinterventional catheter of the present invention includes a filterconfigured to cooperate with a reservoir to ensure that embolic materialcaptured by the filter is not inadvertently released when the filter iscontracted for removal. More preferably, the device of the presentinvention includes a filter that seals the reservoir to prevent embolicmaterial from escaping the filter during contraction and removal of thefilter from the patient's vessel.

Referring now to FIG. 2, exemplary catheter 20 constructed in accordancewith the principles of the present invention is described.Illustratively, catheter 20 comprises a stent delivery system, althoughit should be understood that the system could alternatively comprise adilatation system, atherectomy system or other interventional diagnosticor therapeutic system.

Catheter 20 comprises catheter shaft 21 having distal end 22 andproximal end 23. Shaft 21 is slidably disposed within sheath 24 havingdistal end 25 and proximal end 26. Catheter 20 further comprises adistal region carrying a diagnostic or therapeutic end effector,illustratively balloon 27, inflation port 28 in communication withinterior of the balloon, optional radiopaque markers 29, 30 and 31, andfilter 32. Filter 32 comprises plurality of self-expanding struts 33that support filter mesh 34, as described herein below.

Catheter 20 further comprises a guide wire lumen through which guidewire 35 may be slidably disposed. For over-the-wire use, the guidewirelumen extends from the distal end 22 to a port at proximal end 23 ofcatheter 20. Alternatively, rapid-exchange functionality, the guide wirelumen may extend from distal end 22 to a port comprising a lateral skivein the exterior surface of catheter shaft 21 about 8-10 centimetersproximal of filter 32. In either case, the guidewire lumen extendsthrough the distal region of catheter shaft 21 including filter 32 andthe end effector.

Sheath 24 optionally may include radiopaque marker 36 disposed at distalend 25 to permit fluoroscopic confirmation of the location of thesheath. Illustratively, balloon 27 has plastically deformable stent 37disposed on its exterior surface, although any suitable stent anddelivery mechanism may be employed with the embolic protection system ofthe present invention.

Catheter shaft 21 and sheath 24 preferably are formed of flexiblebiocompatible materials, such as polyethylene, polyurethane, PEBAX,nylon and other polymers typically used in catheter construction.Catheter shaft 21 optionally may comprise carbon nanotubes or otheradditives for added strength. Sheath 24 likewise may be formed in aconventional manner from known catheter materials. Balloon 27 preferablycomprises a non-compliant or semi-compliant material, such aspolyethylene or nylon, and may be constructed using balloon moldingtechniques that are per se known.

Referring now also to FIGS. 3A and 3B, which omits filter mesh 34 forclarity, catheter shaft 21 includes reduced diameter section 38 disposedadjacent to filter 32. Reduced diameter section 38 is shorter than thelength of struts 33, so that when the struts are contracted againstcatheter shaft 21, filter 32 and reduced diameter section 38 cooperateto form reservoir 39. Accordingly, as depicted in FIG. 3A, when struts33 are contracted against the catheter shaft, the struts span the lengthof reduced diameter section 3, and together with filter mesh 34,positively seal reservoir 39. This in turn prevents the escape ofembolic material captured within the reservoir.

In addition, because struts 33 are not expected to deflect appreciablyinto reduced diameter section 38 during distal advancement of sheath 24,advancement of the sheath will not squeeze or dislodge captured embolicmaterial towards the open end of the filter. Consequently, the risk thatemboli will be released from the filter into the blood flow duringcontraction and removal of the catheter is greatly reduced relative topreviously-known catheter designs, such as depicted in FIG. 1.

In a preferred embodiment, sheath 24 has an inner diameter of 6.5 Frenchand catheter shaft 21 has an outer diameter of approximately 5 French,narrowing to a diameter of about 3 French at reduced diameter section40. Catheter 20 preferably has a length appropriate for over-the-wire orrapid exchange use, as may be desired for a particular application.

Filter mesh 34 preferably comprises a mesh having a pore size selectedto allow the passage of blood, but not emboli, through the filter.Illustratively, filter mesh has a pore size less than 500 micrometers,and more preferably, 200 micrometers or less. Filter mesh 34 may beattached to struts 32 using a suitable adhesive, bonding, sonic welding,or other method known in the art.

Referring now also to FIGS. 3 and 4, struts 33 are coupled to mountingring 40, which is affixed to catheter shaft 21 proximal of reduceddiameter section 38. Struts 33 are provided in sufficient number so thatthe outer edge of the filter assumes a substantially circular shape thatcontacts the entire interior circumference of a target vessel whendeployed. Preferably, the filter mesh is supported by at least fourstruts, and more preferably, six, eight or more struts.

Struts 33 may comprise wire elements that are bonded to mounting ring40. Alternatively, as depicted in FIGS. 4A and 4B, struts 33 andmounting ring 40 are integrally formed from a tube or flat sheet ofmetal, e.g., by laser cutting or etching. Struts 33 and mounting ring 40preferably comprise a resilient metal alloy, and more preferably, asuperelastic shape memory alloy, such as a nickel-titanium alloy.Although struts 33 are depicted as having a generally rectangular shape,it should be appreciated that the size, shape, geometry, and number ofstruts 33 may be varied to suit different applications.

As depicted in FIGS. 3A and 3B, catheter shaft 21, including reduceddiameter section 38, may be integrally molded or machined from a tube ofsuitable biocompatible polymer. Alternatively, reduced diameter section38 may comprise a short length of metal alloy hypotube, such asstainless steel, which is bonded at its proximal and distal ends tocatheter shaft 21. This alternative construction advantageously mayprovide additional strength to the catheter in the vicinity of thereduced diameter section, and enhance pushability of the distal end ofthe catheter, especially with respect to a lesion comprising denseplaque.

Struts 33 preferably self-expand from the closed position depicted inFIG. 4A to the open position depicted in FIG. 4B upon proximalretraction of sheath 24. Struts 33 alternatively may comprise a shapememory alloy that is thermally actuated to transition between the openand closed position. For example, struts 33 may comprise anickel-titanium alloy in which the expanded shape depicted in FIG. 4Bhas been impressed at high temperature. After placement of catheter 20and retraction of sheath 24, a bolus of warm water may be injectedaround catheter 20, e.g., through the introducer catheter, to heat thestruts to transition struts 33 and filter 32 to the deployed position.As a further alternative, mounting ring 40 and struts 33 may beresistively heated to transition the struts to the deployed position. Inany of the foregoing embodiments, struts 33 are returned to thecontracted position for removal by advancing sheath 24 to contact andcollapse the struts against catheter shaft 21.

Still referring to FIGS. 4A and 4B, struts 33 may include radiopaquemarkers 41, visible under a fluoroscope, to confirm deployment of thefilter 32. Markers 41 when deployed will have a substantially largercircumference than markers 29, 30, and 31 on catheter shaft 21 andmarker 36 on sheath 24, thereby to facilitate rapid differentiationbetween filter 32, sheath 24 and catheter shaft 21.

Referring now to FIGS. 5A-5F, a method of using catheter 20 of FIG. 1 isdescribed to protect against embolism during iliac stenting. Withrespect to FIG. 5A, the patient is prepped and the femoral artery isaccessed percutaneously or via cutdown and an introducer (not shown) isplaced to establish access to the patient's vessel V. Guidewire 35 isplaced across lesion L and catheter 20 then is advanced along theguidewire until the stent is disposed across lesion L, as determined byfluoroscopic visualization of markers 30 and 31. Blood flow F is towardsthe operator, i.e., from the distal-to-proximal direction relative todevice 10.

Once the position of catheter 20 is confirmed, sheath 24 is retractedproximally while holding catheter shaft 21 stationary. As depicted inFIG. 5B, sheath 24 is retracted to expose balloon 27, stent 37 andfilter 32. As the sheath is retracted proximal to filter 32, struts 33cause the filter to deploy so that filter mesh 34 spans the vessel.Proper retraction of sheath may be confirmed by using a fluoroscope todetermine the relative positions of markers 29 and 27.

Balloon 27 then may be inflated by infusing contrast, saline or carbondioxide through the inflation port and into balloon 27. As balloon 27inflates, stent 37 is expanded into contact with lesion L, compressingthe lesion against the vessel wall and restoring patency to the vessel.During stent deployment, pieces of plaque are released from lesion L,forming emboli E. Emboli E are carried downstream by blood flow F andare captured by filter 32 and are deposited in reservoir 38, as depictedin FIG. 5C.

Referring now to FIG. 5D, after deployment of stent 37, balloon 27 isdeflated. This process may release addition emboli E that are capturedin filter 32. Sheath 24 is then advanced distally to cause struts 33 andfilter mesh 34 to collapse and seal reservoir 38. As depicted in FIG.5E, as sheath 24 is further advanced in the distal direction to coverballoon or the balloon is retracted, emboli are retained within thereservoir and cannot escape into the blood flow.

Referring to FIG. 5F, once sheath 24 has been advanced over filter 32and/or balloon 27, catheter 20 may be removed, followed by removal ofguide wire 35. Once catheter 20 is removed from the patient, emboli Ecollected in reservoir 38 may be examined. It should be appreciated thatthe foregoing method may be employed without stent 37 present oncatheter 20, in case a simple dilatation procedure is desired.

Referring now to FIGS. 6A and 6B, an alternative embodiment of a filtersuitable for use in the catheter of the present invention is described.In particular, filter 50 may be directly substituted for filter 32 incatheter 20 of FIG. 1. In the following description, except wherespecifically noted, primed reference numbers refer to the correspondingstructure of the embodiment of FIG. 1. Thus, for example, catheter 20′of FIG. 6A is shown disposed in vessel V and includes catheter shaft 21′slidably disposed within sheath 24′. Balloon 27′ carries stent 37′ fordeployment within lesion L.

Filter 50 comprises plurality of struts 51 coupled at their proximalends to catheter shaft 21′. The distal ends of each of struts 51includes a concave indentation 52 which slopes outward to define opening53 of the filter. Struts 51 are covered with filter mesh 54, forexample, ePTFE having a multiplicity of pores 55, sized as describedhereinabove. As depicted in FIG. 6A, concave indentations 52 form neck56 that give the filter an amphora shape in the deployed position. Inaccordance with the principles of the present invention, the portion offilter 50 proximal of neck 56 defines reservoir 57 that retains emboli Ecaptured by filter 50 during deployment of stent 37′.

Struts 51 operate in a manner similar to that described above for filter32. In particular, struts 51 are held in a contracted delivery positionby sheath 24′, and self-expand radially outward to the amphora shapeillustrated in FIG. 6A when sheath 24′ is retracted proximally.Preferably, struts 51 comprise a shape memory alloy that has beentrained, using known techniques, to retain concave indentations 52. Thesloping surface of opening 53 is shaped so that embolic materialliberated by actuation of the end effector, illustratively deployment ofstent 37′ by balloon 27′, are funneled past neck 56 into the proximalportion of the filter.

Struts 51 are configured to collapse towards the exterior surface ofcatheter shaft 21′ when sheath 24′ is advanced distally upon completionof actuation of the end effector to return filter 50 to its deliveryposition. In accordance with one aspect of the present invention,concave indentations 52 of struts 51 contact the exterior surface of thecatheter shaft 21′ before the portion of the filter proximal to neck 56.In this manner, as sheath 24′ is advanced distally, the struts sealreservoir 57, thereby preventing embolic material captured within thereservoir from being expelled past neck 56 of the filter. Accordingly,further advancement of sheath 24′ over filter 50 cannot squeeze embolicmaterial from the filter, reducing the risk of embolization duringcontraction and removal of the catheter.

Although preferred illustrative embodiments of the present invention aredescribed above, it will be evident to one skilled in the art thatvarious changes and modifications may be made without departing from theinvention. It is intended in the appended claims to cover all suchchanges and modifications that fall within the true spirit and scope ofthe invention.

1. An interventional catheter for use in a vessel, comprising: anelongated shaft having an exterior surface, a proximal end, a distal endand a distal region having a diagnostic or therapeutic end effector, anda guide wire lumen extending the distal region; a filter coupled to theexterior surface of the elongated shaft in the distal region proximal tothe end effector, the filter comprising a plurality of struts supportinga filter mesh, each one of the plurality of struts having a proximal endand a distal end, the proximal ends of the plurality of struts coupledto the elongated shaft, the struts configured to transition between acontracted position, wherein the distal ends of the struts contact theexterior surface of the elongated shaft, and an expanded position,wherein the distal ends of the struts contract an interior surface ofthe vessel and define a distal opening of the filter, the filter and theexterior surface of the elongated shaft cooperating to define areservoir for retaining emboli captured by the filter; and a sheathhaving a distal end slidably disposed on the elongated shaft, the sheathmovable from a retracted position, wherein the distal end of the sheathis located proximal of the filter, to an extended position, wherein thedistal end of the sheath collapses the filter against the exteriorsurface of the elongated shaft to seal the reservoir and prevent embolifrom passing beyond the distal opening of the filter.
 2. The catheter ofclaim 1 wherein the reservoir further comprises a reduced diametersection of the elongated shaft, the plurality of struts spanning theshaft in the contracted position.
 3. The catheter of claim 1 wherein theend effector comprises a balloon.
 4. The catheter of claim 3 furthercomprising a stent disposed on the balloon.
 5. The catheter of claim 1wherein the filter mesh has a multiplicity of pores, the size of thepores sufficient to permit blood to pass through the filter, but tocapture embolic material.
 6. The catheter of claim 5 wherein the poresize is smaller than 500 micrometers.
 7. The catheter of claim 1 whereinthe plurality of struts comprises four or more struts.
 8. The catheterof claim 1 further comprising one or more radiopaque markers affixed tothe elongated shaft.
 9. The catheter of claim 1 further comprising oneor more radiopaque markers affixed to plurality of struts.
 10. Thecatheter of claim 1 wherein the struts self-expand upon retraction ofthe sheath.
 11. The catheter of claim 1 wherein each strut includes aconcave indentation adjacent to the distal end of the strut.
 12. Thecatheter of claim 11 wherein the concave indentations of the pluralityof struts give the filter an amphora shape when the struts are in theexpanded position.
 13. The catheter of claim 12 wherein a proximalportion of the filter defines the reservoir.
 14. The catheter of claim11 wherein the concave indentation is configured so that when the sheathis advanced to urge the plurality of struts to the contracted position,the distal ends of the plurality of struts contact the elongated shaftbefore more proximally-located portions of the struts.
 15. A catheterfor use in an interventional or diagnostic procedure in a vessel, thecatheter comprising: an elongated shaft having a exterior surface and adistal region having a diagnostic or therapeutic end effector and aguide wire extending through the distal region; a filter coupled to theelongated shaft in the distal region proximal to the end effector, thefilter having a delivery position, wherein the filter is contracteddistal against the exterior surface of the elongated shaft, and adeployed position, wherein a distal edge of the filter contacts aninterior surface of the vessel, the filter and the exterior surface ofthe elongated shaft cooperating to define a reservoir for retainingemboli captured by the filter; and a sheath having a distal end slidablydisposed on the elongated shaft, the sheath movable from a retractedposition, wherein the distal end of the sheath is located proximal ofthe filter, to an extended position, wherein the distal end of thesheath causes the filter to contact the exterior surface to seal thereservoir and prevent dislodgement of emboli beyond the distal edge ofthe filter.
 16. The catheter of claim 15 wherein the reservoir furthercomprises a reduced diameter section of the elongated shaft.
 17. Thecatheter of claim 15 wherein the filter has a multiplicity of pores, thesize of the pores sufficient to permit blood to pass through the filter,but to capture embolic material.
 18. The catheter of claim 17 whereinthe pore size is smaller than 500 micrometers.
 19. The catheter of claim15 wherein the filter further comprises a plurality of struts.
 20. Thecatheter of claim 15 further comprising one or more radiopaque markersaffixed to one of the elongated shaft or the sheath.
 21. The catheter ofclaim 15 wherein the filter self-expands upon retraction of the sheath.22. The catheter of claim 15 wherein the filter comprises a plurality ofstruts, each strut having a proximal end coupled to the catheter and adistal end including a concave indentation.
 23. The catheter of claim 22wherein the concave indentations of the plurality of struts give thefilter an amphora shape in the deployed position.
 24. The catheter ofclaim 23 wherein a proximal portion of the filter defines the reservoir.25. The catheter of claim 24 wherein the concave indentation isconfigured so that when the sheath is advanced to transition the filterto the delivery position, the distal ends of the struts contact theelongated shaft before more proximally-located portions of the struts.